Range safety device

ABSTRACT

A range safety device for practice missiles is constructed to be mounted in the warhead of the missile to continuously monitor the entire flight of the missile. If the missile accelerates beyond prescribed limits of the guidance is wrong, the range safety device shuts off the rocket motor and destructs the warhead section, thus terminating the flight. The device independently monitors missile trajectory without the aid of ground based tracking equipment. The warhead section of the missile is only destroyed at a predetermined time after firing so as to avoid danger to the crew operating the missile.

Umted States Patent 3,695,142 Benson et al. 1 Oct. 3, 1972 RANGE SAFETY DEVICE 3,149,568 9/ I964 Gerber ..244/3.l2 X 72 Inventors: H y R. Benson Dover; Milton v Kmzelman Ashley, Jr., lselin, both of NJ. Primary Exammer-Samuel W. Engle Asslgneei The Umted states of Amen as AttmeyHarry M. Saragovitz, Edward J. Kelly, Her- :fil y the secretary of the hen Berl and Ernest F. Weinberger my [22] Filed: June 8, 1971 ABSTRACT [211 App] 151,084 A range safety device for practice missiles is constructed to be mounted in the warhead of the missile to continuously monitor the entire flight of the missile. [52] US. Cl. ..89/1-812, 89/1314, 89/65, If the missile accelerates beyond prescribed limits of I 102/ 703L235! Lu the guidance is wrong, the range safety device shuts {51] 2 off the rocket motor and destructs the warhead sec- [58] 0 re 70 49 g tion, thus terminating the flight. The device indepen- I dently monitors missile trajectory without the aid of ground based tracking equipment. The warhead sec- [56] References Cited tion of the missile is only destroyed at a predeter- UNITED STATES PATENTS mined time after firing so as to avoid danger to the crew operating the missile. 2,880,672 4/1959 Menke et al ..89/l.8l2 3,098,41 l 7/1963 Fry, Jr. ..89/1 .812 11 Claims, 4 Drawing Figures 32 12 2 chiljllisgbgE RANGE SAFETY DEVICE SECTION 54 FUZE (sco- SIGNAL) C0 54 @L MONITOR 29 Bee! 7 56 ACT. 30 EGGS 24 V PWR. SUPPLY "36 MQN|TOR START (ENABLES) 34 LsI 44 28 2.0 sec. FIXED (DIsAeLEs) 52 Z l l 42 TIME FIRE GYRO POWER DEVICE 65 BUTTON INTER- INTER- 7 LOCK LOCK 9 SEC saA i msr DEVICE (DISABLES 2.0 sEc. 60

ENABLE ACCEL DELAY INST CIRCUIT SWITCH Lo Q T,, Q I.o sec, Lo SEC T EC.

PAIENTEDHM I912 3.895.142 sum 1 or 3 FIG.1

INVENTORS HARVEY R. BENSON M LTON v. A HLEY.JR my a 7% H ATTORNEYS RANGE SAFETY DEVICE The invention described herein may be manufactured, used and licensed by or for the Government for governmental purposes without the payment to us of any royalties thereon.

BACKGROUND OF THE INVENTION Long range missiles are normally tested over selected firing ranges, which firing ranges normally are shorter in length than the actual range of the missile. The problem of potentially long range missiles exceeding the selected range when fired on short firing ranges exists with almost all missile systems. In the prior art missile systems, the problem of the missile exceeding the selected range was solved by placing a command destruct device in the missile. The missile was then tracked in flight by a network of ground tracking stations and If the missile was detected deviating from the prescribed trajectory, the range safety officer radioed a destruct signal to the missile.

This prior art system was very unsatisfactory because it restricted firing the long range missiles to ranges which were equipped with expensive and highly complex tracking equipment and required the individual attention and decision of operators to give the destruct signal. There was always the chance that the missile did not receive the destruct signal due to jamming or signal noise. Much of this could occur outside of the control of the operators and might be due to some normal weather conditions as well as lightning or the like.

SUMMARY OF THE INVENTION The range safety device of the present invention avoids the problems of individual attention and decision of operators and, further, does not require the transmission and receipt of radio signals. Further, it does not require ranges equipped with expensive and highly complex tracking equipment. Rather, the range safety device of the present invention is mounted in the warhead section of the missile and independently monitors the missile trajectory without the aid of ground based tracking equipment and does not require independent judgment of operators.

Further, the device, prior to firing of the missile is totally inert and it does not require settings prior to launch.

The range safety device is installed in the practice missile warhead section and remains inert in the warhead section until the missile is fired. Therefore, it has an indefinite storage life as the electrical power supply for the range safety device is actuated only seconds before actual launching of the missile.

The invention is further designed so that the firing crews of the missile do not have to make any settings or perform any operations on the range safety device. With a series of electronic circuits, explosive switches, thermal battery power supplies, fixed time devices and an acceleration sensor, the range safety device continuously monitors the powered phase of the missile trajectory. If excessive deviation is detected, the device sends an electrical destruct signal to the explosive network in the warhead section. If no deviation is detected, the device remains passive until the rocket sustainer motor is shut off, at which time the range safety device deactivates itself. After the rockets sustainer motor is shut off, the missile is not capable of deviating from a selected ballistic trajectory. Thus the deactivation of the range safety device is perfectly proper at that time.

It is an added feature of the range safety device that it is set so that it will destroy the warhead section and missile at a predetennined time (ten seconds) from time T if the initial flight conditions do not exists or are improper. This action further assures safety for the crew as well as safety for the range. Thus, the device can only destruct ten seconds after take-off, a time in which the rocket will be a distance from the launch crew and, additionally, while still within the safety of the limits of the range.

The range safety device of the present invention is mounted in a completely sealed and self contained package. It operates independently of the remaining components of the warhead section, but controls these components for the monitoring and destruction of the warhead section and missile. Summarized, the purpose of the range safety device is to monitor, detect and destroy a missile when it appears to be out of range of its programmed trajectory or range. It has high reliability, a long shelf life, and is fully contained and selfpowered requiring no manual settings by the user.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a warhead practice missile showing the mounting of the range safety device of the present invention therein.

FIG. 2 is a diagrammatic showing of the range safety device of the present invention.

FIG. 3 is a time diagram over the range of flight showing a practice missile with respect to the operation of the range safety device carried on the warhead section thereof.

FIG. 4 is an acceleration-time diagram for the practice missile utilizing the range safety device of the present invention.

In FIG. 1, there is shown the warhead of a practice missile generally designated by the numeral 10. The warhead 10 is for a Lance missile (in one embodiment) and shows the range safety device 12 of the present invention mounted on a flat aluminum plate 14 approximately 18 inches in diameter so as to give the required rigidity to withstand missile forces. All of the range safety device components are fixed to this plate 14. The device 12 has most of its components mounted in an aluminum cover 16, which cover is approximately eleven inches in diameter. The cover 16 with an O-ring seal seals all of the range safety device wiring and components from the elements as well as provides mechanical protection for the internal wiring and components.

Two thermal batteries 20 and 22 are mounted on the aluminum plate 14 on the opposite side from the cover 16. Thermal batteries 20 and 22 are cylinder shaped, hermatically sealed, thermal batteries. Each of the thermal batteries utilizes a small O-ring seal at its mounting flange to maintain environmental seal for the range safety device. The thermal batteries are used to provide power for the range safety device with one battery supplying all of the power that is necessary to complete the range safety devices functions and missions.

There are also provided terminals 24 and 26 which act as input and output connectors for the range safety device 12. The connectors 24 and 26 are mounted on the side of the aluminum plate 14 upon which are mounted the thermal batteries 20 and 22.

Initiation and operation of the range safety device 12 is shown in block diagram form in FIG. 2. The range safety device is designed to be passive and insure safety for the warhead section for an indefinite time. This is achieved by not energizing the high current power sources, i.e., the thermal batteries 20 and 22 until actual firing of the missile, Thus, so long as the batteries are not activated, the missile warhead range safety device 12 remains totally passive.

A discussion of the operation of the range safety device 12 can best be understood by a comparison with the timing diagram in FIG. 3.

At time T the missile fire button 28 is depressed on a missile test set (MTS) 30. On the missile itself, there is a missile guidance section 32 which includes its own 24 volt, l ampere power source 34. Depression of the fire button 28 on missile test set 30 causes the 24 volt supply 34 to apply this power to the practice warhead section which includes the range safety device 12. The 24 volt source is then operative to ignite matches within the thermal batteries and 22 forming part of a power supply 36 on the range safety device 12. This 24 volt launcher power also flows to an electronic fuze 38 igniting its separate thermal batteries and placing it in a stand by condition.

The next function to occur within the range safety device is for a launch safety interlock 40 (LSI) to function. The launch safety interlock 40 will only function when the condition of the range safety device is correct to receive power. Thus, the launch safety interlock 40 will function only when sufficient power is built up in either of the range safety thermal batteries 20 and 22. When this occurs, the launch safety interlock 40 is initiated (T-;,). The launch safety interlock includes time delay switches. Their purpose is to allow sufficient time (2 seconds) for the range safety device thermal batteries to build up to full strength and stabilize over all temperature extremes before placing load upon the thermal batteries and to assure that the range safety device warhead section is ready for launching.

If the launch safety interlock circuit is initiated, allowing the time delay switches to close, then, at T the following actions occur:

a. The launch safety interlock 40 operates through a power interlock 42 to allow power to flow to various components of the range safety device. Such power is then supplied, at time T the fixed time device 44 and to an internal timing switches within the power interlock 42. These internal timing switches provide an additional 2 second delay. This delay is necessary to check the timer 44 for premature operation. If the fixed time device 44 operates at this point in time, it is open circuited by means of an explosive switch. After the two second time delay, power interlock 42 transmits power to the firing/destruct circuit 48.

b. Also at time T the launch safety interlock switches are connected to a gyro interlock 50 wherein a low impedance switch closure is provided by the range safety device which fires a squib 52 that activates the guidance gyros that in turn initiate the booster thrust engine and commence launch.

The output of launch safety interlock 40 is concurrently applied to activate the gyros for launch and to the fixed timed device 44 via power interlock 42 so that the fixed time device commences its timing functions at approximately launch time. The missile cannot be launched without activation of the gyro interlock 50.

Thus at launch time T the fixed time device 44 provides a nine second delay switch closure which, after nine seconds, will send high current power to the range safety device destruct circuit 48.

After the missile is launched, and the missile booster engine shuts off," the missile guidance section 32 sends a boost good guidance signal (BGGS) from signal member 54, (which signal includes a signal responsive to booster engine shut off) to the range safety device BGGS monitor 56. This normally occurs in a proper time frame, i.e., 2 to 6 seconds after takeoff. This electrical signal is actuated by a solid state switch closure. If the boost good guidance signal is absent or in the wrong time frame, the range safety device will detect this change and act accordingly via the BGGS monitor circuit 56. Thus, the BGGS monitoring circuit 56 accomplishes the following tasks:

1. A correct boost good guidance signal will remove the fixed time device 44 from the range safety device circuit by sending disables signal from the BGGS monitor 56 to the fixed time device 44. (before the 9 second delay in fixed time device 44).

2. The BGGS monitor 56 will fuze send a start signal" to the electronic fuze 38 for a plurality of timed outputs which include the sustainer cutoff time, and smoke and flash event.

3. The BGGS monitor will also send a signal to enable delay circuit 58.

The enable delay circuit 58 senses the receipt of the enable signal from BGGS monitor 56 and if it is of sufficient current it will initate a time delay switch within the circuit to give a one second delay.

After the one second delay, the enable circuit 58 passes current to the acceleration switch 60. The one second delay in the enable circuit 58 is provided to allow the missile sustainer motor time to maintain and dampen out the velocity acceleration profile to a zero G level which occurs at the upper portion of the trajectory. This can easily be seen as the one second delay between points A (booster engine shut off) and B in FIG. 4.

The acceleration switch 60 is now actively monitoring the zero-G portion of the missile trajectory over the range C shown in FIG. 4. This acceleration switch is actually calibrated to plus or minus one half G" and will detect changes in G loading in the longitudinal or acceleration axis of the missile.

It should be noted that the range safety device of the present invention is designed merely to detect and destroy missiles or missile warhead sections that are going beyond a prescribed and programmed range. This is accomplished by looking at and monitoring the G portion of the acceleration profile throughout the upper atmosphere (zero G) of the missile trajectory.

It should be noted however, that the range safety device has the capability of detecting and destroying missiles that fall short of their prescribed trajectory by simply utilizing the negative G portion of the acceleration switch. This method of monitoring will detect and destroy only those missile warhead sections that exceed plus twenty percent of the prescribed range.

Once this positive out of range condition is detected by the acceleration switch 60, then the electrical signal is transmitted to a delay unit 62. When the delay unit 62 receives the out of range signal from the acceleration switch 60, it starts to monitor the signal for a given time period (1 second). This out of range signal must be at prescribed voltage and current levels. If the signal is short or transient in nature, the delay unit 62 will detect this signal and remain passive. Should the signal become constant or nearly so, the delay unit will commence to time-out" and a switch closure will occur at one second.

Whenever the delay unit becomes operative, a solid state closure will occur within the delay unit and provide a high current line output to the destruct circuit 48.

If the out of range signal supplied to the delay unit 62 is interrupted for 50 milliseconds or more at any time during the l second time frame in the delay unit 62, the delay unit will reset to zero and wait for the next out of range signal at the proper level.

The destruct circuit 48 becomes active when the high current from either the delay unit 62 or the fixed time device 44 is applied to the circuit. Two functions occur at this time.

I. A sustainer cut off signal is sent to the missile guidance section 32 through a sustainer cut off monitor 64 which shuts down the sustainer engine based on the timing supplied from the electronic fuze 38.

2. After a one second delay, a firing line is completed and the firing circuit supplies a large current to the safe and arm (S&A) device 65 and destruct network 66 which in turn destroys the warhead section and missile.

The alternate path which can activate the range safety device destruct circuit comes from the fixed time device 44. This path is active in the range safety device in only the first ten seconds of a missile flight. The fixed time device 44 will normally be disabled and removed from the firing circuit by the boost good guidance signal from the boost good guidance signal monitor 56. Thus, if at time T as shown in FIG. 3, the missile fails to send the boost good guidance signal, then the fixed time device continues to time out and at 9 seconds from time T the fixed time device completes a high current line to the destruct circuit 48 which then becomes active sending a sustainer cut off signal and then a fire signal which destroys the warhead section and missile.

It should be noted that the fixed time device will normally just be disabled and removed from the firing circuit by the boost good guidance signal at approximately 3 to 6 seconds after time T The purpose of this secondary or alternate pathmode of the range safety device to destruct the warhead section and missile via a fixed time device is an added feature of the range safety device. It provides launcher safety by establishing 10 seconds before a warhead section and missile can be destroyed. Secondly, it provides for destruction of missiles when there are major problems with the missile booster engine or guidance package (boost good guidance signal). Failure of the boost good guidance signal means that the missile could conceivably go any place without the additional destruct safeguard of the range safety device of the present invention.

As shown in FIGS. 3 and 4 when the nine second delay from fixed time device 44 times out, at time T;,, a high current line is completed to the destruct circuit 48 which then becomes active. Then, at time T or point D in FIG. 21, the sustainer cut off monitor 64 received the sustainer cut off signal and cuts off the sustainer motor.

At time T and after the one second delay of 'the destruct circuit 48, a destruct signal is sent to the S&A device 65 and its destruct network 66. At time T the S&A device 65 and destruct network 66 destructs the warhead section and missile.

It should also be noted that, at a predetermined time after time T that is within approximately 2 seconds after liftoff, the sustaining and arming device 65 is armed by rotation of a mechanical device within the missile. This has not been shown as it is not pertinent to the present invention.

It should be noted that in a regular missile launch, wherein the rangesafety device does not destruct the warhead section, the trajectory would be as shown in FIG. 4. In such case, when the missile reaches a point E immediately above its final destination it explodes a smoke and flash unit to indicate and simulate actual firing of the warhead section immediately before impact at point F on the range.

One particular embodiment of the invention has been shown and described, it will, of course, be understood that various changes may be made without departing from the principles of the invention.

We claim as our invention:

1. A range safety device for the warhead section of a practice missile comprising:

electric power means,

activation means for activating said electric power means at a time just prior to a launching of the missile,

launch safety interlock means for preventing launching of said missile if said activation means is not operative, said launch safety interlock means connecting said electric power means to other electrically operated elements of the range safety device after a time delay prior to launching of the missile,

missile sensing means for sensing operation of the missile in flight after launching, and

destruct means operative from said missile sensing means to destruct at least the warhead section of the missile when the missile is not operating in a predetermined manner.

2. The range safety device of claim 1 including mounting means for mounting electric power means,

activation means, launch safety interlock means, missile sensing means and destruct means within the warhead section of the missile.

3. The range safety device of claim 1 wherein said missile sensing means includes boost good guidance sensing means, said boost good guidance sensing means being operative, when an incorrect boost good guidance signal is sensed to initiate operation of said destruct means a predetermined time after launching of the missile.

4. The range safety device of claim 3 wherein said missile sensing means includes a fixed time device, said fixed time device being operative to energize said destruct means a predetermined time after launching, said boost good guidance sensing means being operative to disable said fixed time device at a point in time prior to said predetermined time when said boost good guidance signal reaches a predetermined value.

5. The range safety device of claim 4 wherein, when said boost good guidance sensing means disables said fixed time device it also enable operation of acceleration sensing means, said acceleration sensing means being operated to detect changes in acceleration from a predetermined value, said acceleration sensing means being operative to operate said destruct means when the acceleration is outside of said predetermined value.

6. The range safety device of claim 5 wherein said acceleration sensing means is operative to sense acceleration a predetermined range above and below zero G.

7. The range safety device of claim 6 wherein said acceleration sensing means is operative to only sense acceleration above zero G.

8. The range safety device of claim 4 wherein said boost good guidance sensing means is operative after shutdown of the missile booster engine.

9. The range safety device of claim 4 wherein said electric power means includes at least one thermal battery.

10. The range safety device of claim 9 wherein said activation means are electrically actuated matches.

11. The range safety device of claim 1 wherein said destruct means is first operative to cut off the sustainer engine of the missile. 

1. A range safety device for the warhead section of a Practice missile comprising: electric power means, activation means for activating said electric power means at a time just prior to a launching of the missile, launch safety interlock means for preventing launching of said missile if said activation means is not operative, said launch safety interlock means connecting said electric power means to other electrically operated elements of the range safety device after a time delay prior to launching of the missile, missile sensing means for sensing operation of the missile in flight after launching, and destruct means operative from said missile sensing means to destruct at least the warhead section of the missile when the missile is not operating in a predetermined manner.
 2. The range safety device of claim 1 including mounting means for mounting electric power means, activation means, launch safety interlock means, missile sensing means and destruct means within the warhead section of the missile.
 3. The range safety device of claim 1 wherein said missile sensing means includes boost good guidance sensing means, said boost good guidance sensing means being operative, when an incorrect boost good guidance signal is sensed to initiate operation of said destruct means a predetermined time after launching of the missile.
 4. The range safety device of claim 3 wherein said missile sensing means includes a fixed time device, said fixed time device being operative to energize said destruct means a predetermined time after launching, said boost good guidance sensing means being operative to disable said fixed time device at a point in time prior to said predetermined time when said boost good guidance signal reaches a predetermined value.
 5. The range safety device of claim 4 wherein, when said boost good guidance sensing means disables said fixed time device it also enable operation of acceleration sensing means, said acceleration sensing means being operated to detect changes in acceleration from a predetermined value, said acceleration sensing means being operative to operate said destruct means when the acceleration is outside of said predetermined value.
 6. The range safety device of claim 5 wherein said acceleration sensing means is operative to sense acceleration a predetermined range above and below ''''zero'''' G.
 7. The range safety device of claim 6 wherein said acceleration sensing means is operative to only sense acceleration above ''''zero'''' G.
 8. The range safety device of claim 4 wherein said boost good guidance sensing means is operative after shutdown of the missile booster engine.
 9. The range safety device of claim 4 wherein said electric power means includes at least one thermal battery.
 10. The range safety device of claim 9 wherein said activation means are electrically actuated matches.
 11. The range safety device of claim 1 wherein said destruct means is first operative to cut off the sustainer engine of the missile. 